Antonio Bianchini

Recent studies show that solar activity exhibits a complex array of oscillatory behaviors spanning from monthly to millennial scales. Among these, the 11-year Schwabe cycle stands out as the most widely recognized solar oscillation. A number of solar oscillations appear to influence Earth's climate and offer promising avenues for understanding and forecasting climate variability. The origin of this array of solar cycles is still debated within the scientific community. One prevailing view links solar cycles entirely to internal magnetic dynamo processes operating inside the Sun. An alternative hypothesis suggests that plan- etary gravitational interactions and orbital configurations may modulate the solar dynamo itself, introducing specific periodic solar oscillations. This study examines key observational findings that support the planetary hypothesis of the connection of solar variability with climate dynamics. It is shown that planetary-induced spectral features closely align with the dominant solar and climate cycles across a broad range of temporal scales.

A statistical analysis was applied to Northern Hemisphere land surface temperatures (1850–2018) to try to identify the main drivers of the observed warming since the mid-19th century. Two different temperature estimates were considered—a rural and urban blend (that matches almost exactly with most current estimates) and a rural-only estimate. The rural and urban blend indicates a long-term warming of 0.89 °C/century since 1850, while the rural-only indicates 0.55 °C/century. This contradicts a common assumption that current thermometer-based global temperature indices are relatively unaffected by urban warming biases. Three main climatic drivers were considered, following the approaches adopted by the Intergovernmental Panel on Climate Change (IPCC)’s recent 6th Assessment Report (AR6): two natural forcings (solar and volcanic) and the composite “all anthropogenic forcings combined” time series recommended by IPCC AR6. The volcanic time series was that recommended by IPCC AR6. Two alternative solar forcing datasets were contrasted. One was the Total Solar Irradiance (TSI) time series that was recommended by IPCC AR6. The other TSI time series was apparently overlooked by IPCC AR6. It was found that altering the temperature estimate and/or the choice of solar forcing dataset resulted in very different conclusions as to the primary drivers of the observed warming. Our analysis focused on the Northern Hemispheric land component of global surface temperatures since this is the most data-rich component. It reveals that important challenges remain for the broader detection and attribution problem of global warming: (1) urbanization bias remains a substantial problem for the global land temperature data; (2) it is still unclear which (if any) of the many TSI time series in the literature are accurate estimates of past TSI; (3) the scientific community is not yet in a position to confidently establish whether the warming since 1850 is mostly human-caused, mostly natural, or some combination. Suggestions for how these scientific challenges might be resolved are offered.

The complex dynamics of solar activity appear to be characterized by a number of oscillations ranging from monthly to multimillennial timescales, the most well-known of which being the 11-year Schwabe sunspot cycle. Solar oscillations are important because they also characterize the oscillations observed in Earth’s climate and can thus be used to explain and forecast climate changes. Thus, it is important to investigate the physical origin of solar oscillations. There appear to be two possibilities: either the oscillations in solar activity are exclusively controlled by internal solar dynamo mechanisms, or the solar dynamo is partially synchronized to planetary frequencies by planetary forcings. The latter concept has recently gained support from a growing amount of evidence. In this work, we provide an overview of the many empirical facts that would support a planetary hypothesis of the variability of solar activity and emphasize their importance for climate research. We show that the frequencies produced by the complex interactions of all of the planets are coherent with the major solar activity and climate cycles, from monthly to multimillennial timescales, including the well-known Schwabe 11-year solar cycle. We provide some persuasive theoretical and empirical support for the planetary hypothesis of solar and climate variability.

Commenting the 11-year sunspot cycle, Wolf (1859, MNRAS 19, 85–86) conjectured that “the variations of spot-frequency depend on the influences of Venus, Earth, Jupiter, and Saturn.” The high synchronization of our planetary system is already nicely revealed by the fact that the ratios of the planetary orbital radii are closely related to each other through a scaling-mirror symmetry equation (Bank and Scafetta, Front. Astron. Space Sci. 8, 758184, 2022). Reviewing the many planetary harmonics and the orbital invariant inequalities that characterize the planetary motions of the solar system from the monthly to the millennial time scales, we show that they are not randomly distributed but clearly tend to cluster around some specific values that also match those of the main solar activity cycles. In some cases, planetary models have even been able to predict the time-phase of the solar oscillations including the Schwabe 11-year sunspot cycle. We also stress that solar models based on the hypothesis that solar activity is regulated by its internal dynamics alone have never been able to reproduce the variety of the observed cycles. Although planetary tidal forces are weak, we review a number of mechanisms that could explain how the solar structure and the solar dynamo could get tuned to the planetary motions. In particular, we discuss how the effects of the weak tidal forces could be significantly amplified in the solar core by an induced increase in the H-burning. Mechanisms modulating the electromagnetic and gravitational large-scale structure of the planetary system are also discussed.

One of the most famous climate oscillations has a period of about 60 years. Although this oscillation might emerge from internal variability, increasing evidence points toward a solar or astronomical origin, as also argued herein. We highlight that the orbital eccentricity of Jupiter presents prominent oscillations with a period of quasi 60 years due to its gravitational coupling with Saturn. This oscillation is found to be well correlated with quite a number of climatic records and also with a 60‐year oscillation present in long meteorite fall records relative to the periods 619–1943 CE. Since meteorite falls are the most macroscopic aspect of incoming space dust and their motion is mostly regulated by Jupiter, we propose that the interplanetary dust influx also presents a 60‐year cycle and could be forcing the climate to oscillate in a similar manner by modulating the formation of the clouds and, therefore, the Earth's albedo.

The high-resolution Jet Propulsion Laboratory DE431 and DE432 planetary ephemeris are used to evaluate the instantaneous eccentricity functions of the orbits of the planets of the solar system from 13 000 BC to 17 000 AD at different time scales. Spectral analyses are performed to determine the frequencies and the amplitudes of the detected perturbations from 0.1-year to 10 000-year periods. Taken as contiguous pairs (Mercury-Venus, Earth-Mars, Jupiter-Saturn, and Uranus-Neptune), we found anti-phase patterns between contiguous planets at specific time scales (30 000 years): namely, the eccentricity of one planet increases while the other decreases. Venus and Earth instead appear in phase. However, on shorter time scales the phase coupling becomes more complex and irregular. Yet, Jupiter and Saturn present a π/2 phase coupling at the 1000-year scale. Periodogram analysis of the planetary eccentricity functions shows several fast fluctuations whose magnitudes indicate the strength of their mutual interactions where the Jovian planets significantly perturb the orbits of the inner planets. Besides, the wavelet power spectrum and wavelet squared coherence spectrum analyses are adopted to examine the relationships in time-frequency space between the eccentricity functions of each couple of terrestrial and Jovian planets. The analysis reveals the complexity and the evolution of the gravitational couplings perturbing each other planetary orbits. In some cases and for specific frequencies, this analysis technique also led to the discovery that the coherence phase can rotate clockwise or anticlockwise. The eccentricity function of the orbit of Jupiter presents large oscillations with periods of about 60 and 900- 960 years, mostly due to the interaction with Saturn. These oscillations also correspond to oscillations found in several geophysical records. The eccentricity functions of Uranus and Neptune are characterized by a large 4300-year oscillation. The eccentricity function of Pluto is characterized by a large nearly 20 000-year modulation.

The cataclysmic variable SDSS J214354.59+124457.8 (hereafter SDSS J214354) was observed photometrically on sixty one nights between 2012 July 28 and 2019 May 26. The long term variation of this object shows changes between two phases; a dwarf nova type and a novalike. This implies that the object belongs to the group of Z Cam type stars. The timing analysis of the light curve reveals a periodic signal at 0.13902(5) d, which we identify as the superhump period. However, the fractional superhump excess of 10 per cent longer than the orbital period is exceptionally large. We obtained a mass ratio of ∼0.4, which is above the accepted upper limit of q = 0.33 for the formation of superhumps. We suggest that the object contains a secondary with an evolved core. With an orbital period of 0.126 d, SDSS J214354 is situated at the upper border of the period gap. The long term light curve of SDSS J214354 is similar to those of Z Cam type stars which are characterized by recurring standstills, followed by short intervals with DN type outbursts. Therefore, we conclude that SDSS J214354 is a new member of the Z Cam type stars.